Method and apparatus for producing steam

ABSTRACT

This invention relates to a method and apparatus for producing steam utilizing an external irregular supply source such as an incinerator plant, a waste boiler, a nuclear plant, etc., combined with a twin furnace having a first evaporator compartment and a second superheater and reheating compartment.

United States Patent Rawdon, Jr.

[54] METHOD AND APPARATUS FOR PRODUCING STEAM [72] Inventor: Albert H. Rawdon, Jr., Shrewsbury, Mass.

[73] Assignee: Riley Stoker Corporation, Worcester,

Mass.

[22] Filed: July 17, 1969 [21] Appl. No.: 842,460

[52] U.S. Cl ..122/1, 122/7, 122/33 [5 1 1 Int. Cl ..F22b 33/00 [58] Field ofSearch ..l22/1,2, 7, 33,485; 60/73 [56] References Cited UNITED STATES PATENTS 1,407,717 2/1922 Witte ..122/7 5754/1 mv 20 I5 Ewe/v42 50am:

[ 51 May 23, 1972 2,420,647 5/1947 Boland 122/478 2,593,435 4/1952 Frisch..... 122/485 2,959,014 11/1960 Artsay ....60/73 3,118,429 1/1964 Hochmuth..... ....l22/7 3,236,209 2/1966 Vandeghen ..122/33 7 Primary ExaminerKenneth W. Sprague Att0rney--Ward, McElhannon, Brooks & Fitzpatrick [57] ABSTRACT 6 Claims, 2 Drawing Figures METHOD AND APPARATUS FOR PRODUCING STEAM This invention relates to an installation for producing steam and more particularly to a system which employs steam from two difierent sources. The first source is an external steam source and includes such steam supply means as incinerator plants, waste heat boilers, nuclear plants, and the like. The volume of this source of steam is irregular by its very nature. The second source of steam is one compartment of a twin furnace. The other compartment of the twin furnace is where superheating and reheating takes place.

Twin furnaces are common in the art and numerous patents relating to such furnace structures have been noted. Some of these patents show partitions between evaporators and superheaters such as U.S. Pat. No. 3,223,074 dated Dec. 14, 1965, and some patents show partitions between completely independent boilers, such as U.S. Pat. No. 1,955,777 dated Apr. 24, 1934, which is used in the marine field, for example. Generally, the pressure balance between the compartments is achieved by providing holes through the partition wall. Also, various type furnaces have been employed for incinerating garbage, but they have not been very efficient in operation. Applicant has discovered a novel combination of elements combined in such a way as to afford a very economical, efficient and practical solution of the difficulties and problems above discussed, as will become apparent as the description proceeds.

Briefly, my concept in one form thereof, contemplates the provision of an installation for producing steam comprising a first external irregular steam source, a twin furnace having a first evaporating compartment and a second superheater and reheating compartment. A mixing header is provided for receiving steam from said external source and from said first evaporator compartment. Means are provided for controlling the output of the first compartment to compensate for the variation in output of the external source. The second compartment of the twin furnace receives saturated steam from the mixing header and superheats same before it is passed to the point of utilization, such as a steam turbine. In one form of the invention, steam passes through the high pressure cylinder of the turbine and then a portion thereof is returned to the second compartment of the twin furnace for reheating before passing again to the initial stages of the turbine.

According to one aspect of my invention, conventional fossil fuel is fired in both furnaces, and separate combustion contrials are employed for each compartment. The evaporator compartment of the furnace is fired to maintain pressure and the superheater and reheating compartment is fired to maintain temperature. Dampersare located on each side of a division wall between the two compartments to maintain constant pressure in each chamber in order to prevent large deflections, and as the pressure builds up, it puts the division wall under tension which enables a reduction of the necessary reinforcing steel required on the other pressure walls of the furnace.

According to another aspect of my invention, I provide a new and improved method of producing steam comprising the steps of receiving steam from an external irregular source in a mixing header, and receiving a compensating quantity of steam from an evaporator compartment of a twin boiler corresponding to the quantity of steam received from said external source, mixing said two sources of steam, passing said steam to a superheater and reheating compartment of said twin furnace, and then passing the steam to a point of utilization, such as a steam turbine, for example.

There has thus been outlined rather broadly the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter which will form the subject of the claims appended hereto. Those skilled in the art will appreciate that the conception on which this discl sure is based may readily be utilized as the basis for the designing of other structures for carrying out the several purposes of the invention. It is important, therefore, that this disclosure be regarded as including such equivalent constructions as do not depart from the spirit and scope of the invention.

One embodiment of the invention has been chosen for purposes of illustration and description,-and is shown in the accompanying drawings, forming a part of the specification wherein:

FIG. 1 is a side elevation, partially schematic, of a steam producing installation constructed in accordance with the concept of my invention; and

FIG. 2 is a plan view, drawn on a reduced scale, of the twin boilers employed in my steam producing installation.

In the embodiment illustrated, an installation for producing steam includes a first external irregular source of steam 10, which may be an incinerator plant, a waste heat boiler, a nuclear power plant, or the like. A twin furnace, indicated generally at 12, is provided having a first evaporator compartment 14, a dividing wall 15, and a second superheater and reheating compartment 16. A mixing header 18 receives steam from the first external irregular source of steam 10 via valve 20 and pipeline 22, and from the first evaporator compartment as indicated by arrows 24, FIG. 1. Means, as will be pointed out more fully hereinafter, are provided for controlling the output of the first compartment to compensate for the variation in output of the external source.

The second compartment 16 of the twin furnace receives saturated steam from the mixing header via pipeline 26, provided for the purpose. The steam is superheated in the second compartment to the desired temperature before it is passed to the first stage of a steam turbine 28, via pipeline 30. The turbine drives a generator 31 in a conventional manner. The steam passes through the turbine and out through the exhaust pipeline 32 to a feed water processing plant 34. A portion of the steam is bled off from'the turbine via pipeline 36 and re heated in the second compartment 16 of the twin furnace. After reheating, the steam is returned to the turbine 28, via pipeline 38. After the exhaust steam is condensed and treated in a conventional manner, it is returned to the steam and waterdrum 39, via feed line 40 and feed valve 42.

Conventional fossil fuel 44 is fired in the evaporating compartment 14 of the furnace 12. This compartment is provided with controls 46 and is fired to maintain pressure. Conven tional fossil fuel 48 is also fired in the superheater and reheater compartment l6 of the furnace. This compartment is provided with controls 50 and is fired to maintain temperature.

The evaporating compartment 14 has a damper 52, and the superheater and reheater compartment 16 has a damper 54. That is, one damper is provided on each side of the divider wall 15 and they serve to maintain constant preselected pressure in each chamber in order to prevent large deflections. In one form of the invention the divider wall is of welded web construction so that the pressure must be substantially equal on both sides thereof. As best seen in FIG. 2, as the pressure builds up, forces 56 indicated by the arrows act on the walls of the furnace, thereby placing the dividing wall 15 under tension which enables a reduction of the necessary reinforcing steel required on the other pressure walls of the furnace 12.

The evaporating compartment 14 is so sized that from about 10 to about 25 percent of the saturated steam is always made therein so as to keep it on a live bank. Should the external source 10 of saturated steam be shut down or reduced in quantity from the desired amount, then the remainder is made up from the evaporating compartment 14 of the twin furnace. It will be appreciated that the walls of the furnace are lined with tubes such as tubes 62 in the evaporating compartment. These tubes lead from the steam and water drum 39 to the lower drum 63. Superheater tubes 64 and reheater tubes 65 line the walls in the superheater and reheater compartment. However, a few evaporator tubes 62 are led along the walls of a superheater and reheater compartment 16, as indicated by the broken lines 66, FIG. 1. This serves to assure minimum evaporation which is required to keep the water envelope at a good even temperature. A few superheater tubes 64 are crisscrossed so as to draw steam evenly from drum 39.

As pointed out hereinbefore the evaporating compartment 14 is fired for pressure. A master controller 67 for pressure is disposed on the external side of the mixing header 18, whereas in conventional installations this controller is disposed at the turbine inlet. Since the desired pressure at the outlet of the header is known and the pressure of the external source of steam is known, the evaporating compartment 14 is fired to obtain the desired pressure.

lt will thus be seen that the present invention does indeed provide an improved method and apparatus for producing steam utilizing an external irregular source thereof, which is superior in simplicity, economy and efficiency as compared to prior art such systems.

Although a particular embodiment of the invention is herein disclosed for purposes of explanation, various modifications thereof, after study of this specification, will be apparent to those skilled in the art to which the invention pertains.

What is claimed and desired to be secured by Letters Patent is:

1. An installation for producing steam comprising a twin furnace having a first evaporating compartment and a second superheater and reheating compartment, an external irregular source for supplying steam, a mixing header for receiving steam from said external irregular source and from said first evaporating compartment, means for controlling the output of said first evaporating compartment to compensate for the variation in output of the external steam source, means for passing the steam from said mixing header to said second compartment, and outlet means for said second compartment, a divider wall separating said compartments, means mounted in each compartment to maintain preselected substantially equal pressure in each compartment to prevent large deflections of said divider wall, whereby said divider wall is under tension when the pressure builds up in said compartments.

2. An installation for producing steam according to claim 1, wherein said evaporating compartment is sized to always supply a minimum offrom about to about 25 percent ofthe saturated steam to said mixing header.

3. An installation for producing steam according to claim 1, wherein the walls of said evaporating compartment are lined with substantially all evaporating tubes and a few superheating tubes, and the walls of said superheater and reheating compartments are lined with substantially all superheating and reheating tubes and a few evaporating tubes.

4. An installation for producing steam comprising a twin furnace having a first evaporating compartment and a second superheater and reheating compartment, an external irregular source for supplying steam, a mixing header for receiving steam from said external irregular source and from said first evaporating compartment, means for controlling the output of said first evaporating compartment to compensate for the variation in output of the external steam source, means for passing the steam from said mixing header to said second compartment, and outlet means for said second compartment, a master pressure controller being mounted on the external side of said mixing header.

5. An installation for producing steam comprising an external irregular source for supplying steam, a twin furnace having a first evaporating compartment and a second superheater and reheating compartment, a mixing header for receiving steam from said external source and from said evaporating compartment, means for controlling the output of said first evaporating compartment to compensate for the variation in output of the external steam source, means for passing the steam from said mixing header to said superheater and reheating compartment, a steam turbine for receiving steam from said superheater and reheating compartment, and means for bleeding ofi a portion of the steam from an intermediate stage of said turbine for reheating in said superheater and reheating compartment, means for firing conventional fossil fuel in each of said compartments, control means for maintaining predetermined pressure in said evaporating compartment, and control means for maintaining predetermined temperature in said superheater and reheating compartment, a divider wall separating said compartments, a damper mounted in each compartment to maintain preselected substantial equal pressure in each compartment to prevent large deflections of said divider wall, whereby said divider wall is under tension when the pressure builds up in said compartments, said evaporator compartment being sized to always supply a minimum of from about 10 to about 25 percent of the saturated steam to said mixing header, the walls of said evaporating compartment being lined with substantially all evaporating tubes and a few superheating tubes, and the walls of said superheater and reheating compartment being lined with substantially all superheating and reheating tubes and a few evaporating tubes, and a master pressure controller mounted on the external side of said mixing header.

6. A method of producing steam comprising the steps of generating steam at an external irregular source, supplying said steam to a mixing header, generating a minimum of from about 10 to about 25 percent compensating quantity of steam in an evaporating compartment of a twin boiler corresponding to the quantity of steam received from said external source, supplying said compensating steam to said mixing header, firing said evaporating compartment to maintain a preselected pressure, passing said steam from said mixing leader to a superheater and reheating compartment of said twin furnace, firing said superheater and reheating compartment to maintain a preselected temperature, controlling damper means for said compartments to maintain both compartments at substantially equal pressure, then passing the steam to a steam turbine, bleeding off a portion of steam from an intermediate stage of said turbine and returning it to said superheater and reheating compartment, recycling the turbine exhaust steam through a feed water plant and back to said boiler.

UNK'ITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,664, 307 Dated May 23 1972 Inventofls) Albert H RaWdOn, Jr

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column .2 line 63 Column 3, line 40 l0 to about 25 percent" should read -l0 percent to about 25 percent-- Column 4, line 40 Signed and sealed this 12th day of September 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents USCOMM-DC 603764 69 uisi GOVERNMEN'I murmur. orncz I969 o-ase-un FORM PO-1OSOHO-69) 

1. An installation for producing steam comprising a twin furnace having a first evaporating compartment and a second superheater and reheating compartment, an external irregular source for supplying steam, a mixing header for receiving steam from said external irregular source and from said first evaporating compartment, means for controlling the output of said first evaporating compartment to compensate for the variation in output of the external steam source, means for passing the steam from said mixing header to said second compartment, and outlet means for said second compartment, a divider wall separating said compartments, means mounted in each compartment to maintain preselected substantially equal pressure in each compartment to prevent large deflections of said divider wall, whereby said divider wall is under tension when the pressure builds up in said compartments.
 2. An installation for producing steam according to claim 1, wherein said evaporating compartment is sized to always supply a minimum of from about 10 to about 25 percent of the saturated steam to said mixing header.
 3. An installation for producing steam according to claim 1, wherein the walls of said evaporating compartment are lined with substantially all evaporating tubes and a few superheating tubes, and the walls of said superheater and reheating compartments are lined with substantially all superheating and reheating tubes and a few evaporating tubes.
 4. An installation for producing steam comprising a twin furnace having a first evaporating compartment and a second superheater and reheating compartment, an external irregular source for supplying steam, a mixing header for receiving steam from said external irregular source and from said first evaporating compartment, means for controlling the output of said first evaporating compartment to compensate for the variation in output of the external steam source, means for passing the steam from said mixing header to said second compartment, and outlet means for said second compartment, a master pressure controller being mounted on the external side of said mixing header.
 5. An installation for producing steam comprising an external irregular source for supplying steam, a twin furnace having a first evaporating compartment and a second superheater and reheating compartment, a mixing header for receiving steam from said external source and from said evaporating compartment, means for controlling the output of said first evaporating compartment to compensate for the variation in output of the external steam source, means for passing the steam from said mixing header to said superheater and reheating compartment, a steam turbine for receiving steam from said superheater and reheating compartment, and means for bleeding off a portion of the steam from an intermediate stage of said turbine for reheating in said superheater and reheating compartment, means for firing conventional fossil fuel in each of said compartments, control means for maintaining predetermined pressure in said evaporating compartment, and control means for maintaining predetermined temperature in said superheater and reheating compartment, a divider wall separating said compartments, a damper mounted in each compartment to maintain preselected substantial equal pressure in each compartment to prevent large deflections of said divider wall, whereby said divider wall is under tension when the pressure builds up in said compartments, said evaporator compartment being sized to always supply a minimum of from about 10 to about 25 percent of the saturated steam to said mixing header, the walls of said evaporating compartment being lined with substantially all evaporating tubes and a few superheating tubes, and the walls of said superheater and reheating compartment being lined with substantially all superheating and reheating tubes and a few evaporating tubes, and a master pressure controller mounted on the external side of said mixing header.
 6. A method of producing steam comprising the steps of generating steam at an external irregular source, supplying said steam to a mixing header, generating a minimum of from about 10 to about 25 percent compensating quantity of steam in an evaporating compartment of a twin boiler corresponding to the quantity of steam received from said external source, supplying said compensating steam to said mixing header, firing said evaporating compartment to maintain a preselected pressure, passing said steam from said mixing leader to a superheater and reheating compartment of said twin furnace, firing said superheater and reheating compartment to maintain a preselected temperature, controlling damper means for said compartments to maintain both compartments at substantially equal pressure, then passing the steam to a steam turbine, bleeding off a portion of steam from an intermediate stage of said turbine and returning it to said superheater and reheating compartment, recycling the turbine exhaust steam through a feed water plant and back to said boiler. 